Mystery oil reservoir?

[maccraith]

I have a feeling I may be about to embarrass myself with this question, but here goes:

I was replacing the left-side driver's foot peg on my '03 R1150R (non ABS) when I glanced up over the muffler in the direction of the air box. To the rear of the air box, I noticed a kind of extension of the air box on the bottom of which was a drain cap. I reached up and turned the cap and carefully released it toward the ground. As I did, oil began to flow out the bottom. Fortunately, I recapped it before I lost much oil.

My obvious (and perhaps stupid) question is, "What is it?" I have looked through all my manuals and tried to google an identification, but no luck. I have also looked under the seat for a possible filler cap but could see none.

Can anyone tell me what the reservoir is for and what, if anything, I should do with or about the oil inside of it?

[wust588]

I'm not absolutely sure, but I think the engine breather vents into the air-box, and over time
oil collects as a result of oil mist?

[kirby]

Merry Christmas!
You have discovered the drain for the airbox!
It should be drained occasionaly.
The crankcase is vented to the airbox because it cleverly helps to manage the pressure in the crankcase. Its a delicate problem, especially on opposed engines like the BMW.
Quite normal for some oil to be in there,the quantity relates to how you ride.

mike :-)

[maccraith]

How 'bout that! I never knew. I wonder if mine has ever been drained . . . 11 years is a long time.

I am curious, Kirby. How does riding style relate to the quantity in this tank?

Thanks for the replies, guys.

[rocky2ie]

I check mine regularly, no sign of oil, it probably burns it instead

[kirby]

How 'bout that! I never knew. I wonder if mine has ever been drained . . . 11 years is a long time.

I am curious, Kirby. How does riding style relate to the quantity in this tank?Thanks for the replies, guys.

Its the air box...where the air filter is.

It is related mostly to high rpm and throttle setting especially while leaned over.(windage on the crank) When I take my rockster to a track day and am pushing it will put about 3 or so ounces..maybe 1/4 cup in the box for a couple hours on the track, but during normal riding very little is ever in there.
I usually check during normal service and always after a fast session. A word, get a shop rag or paper towel ready when you open it just in case!

Merry Christmas!

mike :-)

[maccraith]

How 'bout that! I never knew. I wonder if mine has ever been drained . . . 11 years is a long time.

I am curious, Kirby. How does riding style relate to the quantity in this tank?Thanks for the replies, guys.

Its the air box...where the air filter is.

It is related mostly to high rpm and throttle setting especially while leaned over.(windage on the crank) When I take my rockster to a track day and am pushing it will put about 3 or so ounces..maybe 1/4 cup in the box for a couple hours on the track, but during normal riding very little is ever in there.
I usually check during normal service and always after a fast session. A word, get a shop rag or paper towel ready when you open it just in case!

Merry Christmas!

mike :-)

Fascinating. I never knew of or thought of such a thing. Thanks. :-)

[CycleRob]

A normal track day will involve extended periods of full throttle and high RPMs where oil vapor pushed out by high performance driven blowby gasses will condense in the properly designed gaseous flow routes to the airbox. In that case a little oil in the airbox drain tube is normal. On a street bike there is only one cause that will fill up that airbox drain tube with an alarming "flow" of oil and that is overfilling the engine oil. So many new OilHead owners look at that little circular oil window after a short trip and interpret the oil at the lower part of the window as being VERY, DANGEROUSLY LOW on oil and they will immediately add oil, even if last week it was at the center red dot. This occurs because the engine did not get hot enough for the oil cooler thermostat valve to remain open long enough for both oil coolers to completely drain themselves back into the crankcase sump to raise the oil level to it's true reading in the oil window. Experienced OilHead owners eventually learn that the center-red-dot, 3.75 qt (3.55L) from hot drained empty, should always be the "full" mark. Because of necessary crankcase size/space compromises made during its' engine design, exceeding center-red-dot will effectively encourage more oil burning, which generates heavier than normal combustion chamber deposits to a point where the engine will ping with premium grade gasoline. ALL owners also should know that when the oil level can barely be seen in the lower part of the window (on the centerstand) there is STILL 3 QUARTS OF OIL IN THE ENGINE!! That little known fact is why the paranoia associated with maintaining the oil in the upper part of the sight glass window is a senseless, uninformed, obsessive-compulsive disorder (OCD) that will contaminate the combustion chamber surfaces with carbon deposits, increasing the likelyhood it will "ping" (pre-ignition) from the glowing deposits.

maccraith, If you are not responsible for overfilling the oil level I would not drain the high oil level unless it exceeds the upper-red-circle on the window. If it does go higher than upper-red-circle then Yes, with a cold engine, clean around it then unscrew the drain plug and drain out a small quantity of oil into a container, about a big coffee mug's worth, then screw the drain plug part way back in. Wait a few minutes, check the oil window and repeat if necessary. As for the oil filled airbox drain you should give it a few overnight drain sessions. Ideally you should lift the fuel tank and remove the airbox lid and air filter (oil soaked?) element so you can first wipe out and then solvent clean the accumulated puddle of oil. On my OilHead, which after year one never exceeded center-red-dot, all that came out of the drain tube was dry sand granules that were sucked into the snorkel inlet.

To avoid overfilling the oil at oil change time you should follow this procedure:
1--The engine MUST be VERY HOT before draining. To get it VERY HOT in cold climates, take a 5 mile ride out, turn around, and ride back using the transmission lower gears to maintain 4,000+ RPM at the road speed limit until you get home. Then 5 minutes on the side stand so the oil coolers drain completely . . . and finally put it on the centerstand at the oil drain location.

2--If the engine is too hot you can wait 10 minutes so finger/hand burns are less likely. You should wear rubber or Nitrile gloves, but a plastic baggie will also protect your skin for a short while from hot oil mishaps after the drain plug is removed.

3--After the oil drain flow becomes intermittent drops, tip the bike on the centerstand both ways to about a 5 minute clock angle - - and hold it there several seconds to drain the valve covers, cylinder bores and crankcase internal webbing of residual oil puddles. Doing so ensures the oil will not be overfilled by an incomplete draining -and- it gives the new oil a from-the-bottle new oil look!

4--Reinstall the drain plug and tighten.

5--Use a little oil of the first Qt or L bottle to slowly fill up the new oil filter to the top, covering the metal and contained by the gasket. That decreases the time of zero oil pressure on the oil change start-up. Reach under the engine, lying on you side/back so you can look up into the oil filter tunnel at the filter gasket's machined Aluminum surface and clean it really good. Install the new oil filter without spilling the prefilled oil and tighten it with the cup wrench.

6--Add 3.75 quarts. That leaves 8 ounces remaining in the 4th quart. For Liters, it is 3.55 L or 450 ml left in the 4th Liter bottle.

7--After adding the oil you do not even have to check the oil window as it will LIE to you UNLESS there was a proper hot engine side stand shut down, center stand overnight drainback. Do NOT even THINK of adding ANY more oil until at least 700+ miles later when/if the level gets to lower-red-circle, ONLY determined to be valid and true IF there was a proper very hot engine side stand shutdown and center stand drainback period. Check out the engine crankcase pic below (thanks to RChop) to see how high up the oil window is and the height-length-depth of oil that is there that you can not see!

Don't you feel better now, realizing the lower red ring oil level is NOT an out of oil emergency. To be sure the oil level is close, tip the bike a little bit on the center stand and watch the oil level appear.

FYI, my 2009 F800ST uses less than a half quart in 6,000 miles and I never needed to add oil, even during the personally extended 800 mile break-in period. It is so consistent the dipstick/filler cap is safety wired shut between the 6,000 mile oil changes.



.

[maccraith]

Bob-
I have seen your suggestions/instructions on oil level checking and changing before. And I have followed them; always found them to be accurate and true. This time you have outdone yourself with instruction and explanation. Well done! And thanks again.